Abstract
Aim: The current study was piloted to assess the impact of eugenol nanoemulsion (EUGN) supplementation on growth performance, serum metabolites, redox homeostasis, immune response, and pro-inflammatory reactions in growing rabbits exposed to heat stress.
Methods: A total of 100 male weanling rabbits aged 35 days were alienated into four treatments, each of which contained EUGN at concentrations of 0 (control group; EUGN0), 50 (EUGN50), 100 (EUGN100), and 150 (EUGN150) mg/kg diet (n = 25 per treatment).
Results: Dietary EUGN levels improved (p < 0.05) the body weight, body weight gain, carcass weights, and reduced feed conversion ratio of rabbits. EUGN supplementation increased significantly Hb, Plat and RBCs, while the MCH and ESO were significant decreased compared to control one. Compared with EUGN0 stressed rabbits, all EUGN-experimental groups had reduction in the TG (p<0.01), uric acid, total bilirubin, direct bilirubin and GGT (p<0.01) levels. TAC and GSH-Px were significantly improved by EUGN treatment when compared with the control one (p<0.01), while the EUGN100 exhibited the greatest levels of CAT. Lipid peroxidation (MDA) was significantly decreased in EUGN-treated groups. All pro-inflammatory cytokines IL4, IL-1β and TNF-α were considerably decreased after dietary EUGN supplementation (p<0.05). The serum concentrations of immunoglobulins (IgG and IgG) were significantly improved in rabbits of EUGN150 group.
Conclusion: This study showed that EUGN can be used as a novel feed additive to enhance the growth performance, immune variables, antioxidant, and anti-inflammatory properties of growing rabbits exposed to thermal stress.

Key words: eugenol nanoemulsion; heat stress; growing rabbit; immunity; health